摘要
Gas wiping is a decisive operation in hot-dip galvanizing process. In special, it has a crucial influence on thethickness and uniformity in coating film, but may be subsequently responsible for the problem of splashing. Theprogress of industry demands continuously the reduction of production costs which may relate directly with theincrease of coating speed, and the speed up of coating results in the increase of stagnation pressure in gas wipingsystem in final. It is known that the increase of stagnation pressure may accompany a harmful problem of splashingin general. Together with these, also, from the view point of energy consumption, it is necessary to design anozzle optimally. And there is known that the downward tilting of nozzle using in air knife system is effective toprevent in somewhat the harmful problem of splashing. In these connections, first, we design a nozzle with constantexpansion rate. Next, for the case of actual coating conditions in field, the effects of tilting of the constantexpansion rate nozzle are investigated by numerical analysis. Under the present numerical conditions, it wasturned out that the nozzle of constant expansion rate of p=having a downward jet angle of 5° is the most effectiveto diminish the onset of splashing, while the influence of small tilting of the nozzle on impinging wall pressureitself is not so large.
Gas wiping is a decisive operation in hot-dip galvanizing process. In special, it has a crucial influence on the thickness and uniformity in coating film, but may be subsequently responsible for the problem of splashing. The progress of industry demands continuously the reduction of production costs which may relate directly with the increase of coating speed, and the speed up of coating results in the increase of stagnation pressure in gas wiping system in final. It is known that the increase of stagnation pressure may accompany a harmful problem of splashing in general. Together with these, also, from the view point of energy consumption, it is necessary to design a nozzle optimally. And there is known that the downward tilting of nozzle using in air knife system is effective to prevent in somewhat the harmful problem of splashing. In these connections, first, we design a nozzle with constant expansion rate. Next, for the case of actual coating conditions in field, the effects of tilting of the constant expansion rate nozzle are investigated by numerical analysis. Under the present numerical conditions, it was turned out that the nozzle of constant expansion rate of p = having a downward jet angle of 5^0 is the most effective to diminish the onset of splashing, while the influence of small tilting of the nozzle on impinging wall pres- sure itself is not so large.
关键词
涂层厚度
热浸镀锌
空气影响
优化设计
系统使用
数值分析
镀锌工艺
生产成本
Air-knife, Constant expansion rate nozzle, Impinging pressure, Wall shear stress, Hot-dip galvanizing, Coating thickness, Splashing
